Problem: In 30 years, Stephanie will be 3 times as old as she is right now. How old is she right now?
Solution: We can use the given information to write down an equation about Stephanie's age. Let Stephanie's age be $s$ In 30 years, she will be $s + 30$ years old. At that time, she will also be $3 s$ years old. Writing this information as an equation, we get: $s + 30 = 3 s$ Solving for $s$ , we get: $2 s = 30$ $s = 15$.